The focus of this project is the use of CYP1A1 gene to monitor human exposure to aromatic hydrocarbons, and to explore the molecular basis of CYP1A1 polymorphisms as cancer susceptibility factors in African Americans. A new quantitative reverse transcriptase PCR method for measurement of gene expression in various indicator tissues (frozen blood, nasal epithelial cells, exfoliated bladder epithelial cells), of people exposed to cigarette smoke, creosote and charcoal broiled foods will be developed and validated. This method, which uses a homologous internal standard (HIS) for accurate quantitation, has the promise of becoming a valuable tool in the development of new biomarkers of exposure based on gene expression in small samples of fresh or stored human tissue. The investigators will extend their research into the mechanisms of individual differences in cancer susceptibility, by investigating the biochemical functional significance of two CYP1A1 restriction polymorphisms that they have found to be linked with cancer risk in African Americans. The investigators will determine whether either of these RFLPs are linked with other polymorphisms in the CP1A1, AHR or ARNT genes in African Americans.